北斗卫星反射信号岸基海面高度反演精度的评估

Evaluation of accuracy of shore-based sea surface height inversion based on Beidou satellite reflected signals

北斗B3I信号作为新一代民用码,相较于北斗B1I信号,具有码速率更高、码片宽度更窄等特点。目前,利用北斗卫星导航系统反射测量(BDS-R)技术对北斗B3I信号进行海面高度反演的研究较少。基于此,在2020年9月7日山东威海附近海域,接收B1I/B3I双频段的直射和反射信号数据,分别采用时延-多普勒(DDM)和载波相位延迟进行岸基海面高度反演。通过实测的同比数据验证反演精度,在信号特性和测高方法2个维度评估北斗B1I和B3I信号海面高度反演的性能。结果显示:采用DDM测高方法,B1I频段和B3I频段的反演结果与实测数据的平均绝对误差和均方根误差分别为1.18 m、1.48 m和0.84 m、1.10 m;采用载波相位延迟测高方法,B1I频段和B3I频段的反演结果与实测数据的平均绝对误差和均方根误差分别为0.12 m、0.15 m和0.10 m、0.12 m。由于信号特性差异,B3I频段的DDM测高结果相较于B1I频段的测高结果精度提高了28%;B3I频段的载波相位延迟测高结果精度略优于B1I频段,两者差异不明显。实验对北斗B1I和B3I信号特性和测高方法导致的反演精度差异的评估,证明了B1I和B3I反射信号均能适用于海面高度反演的需求。

Beidou B3I signal,a new generation of civil code,has a higher rate and narrower chip width compared with B1I signal.Currently,there are few studies on the retrieval of sea surface height from B3I signals by using the Beidou reflected signal(BDS-R)technology and no relevant experimental results and accuracy evaluation.This paper usesthe direct and reflected signal data of the B1I/B3I dual band received by the receiver in the sea area near Weihai,Shandong on September 7,2020,and adopts the delay-Doppler-map(DDM)and carrier phase delay methods respectively to carry out shore-based sea surface height retrieval.The measured data was used to confirm the retrieval’s accuracy,and the performance of the B1I and B3I signals’sea surface height retrieval was assessed in terms of both their signal characteristics and their height measuring technique.The results show that the mean absolute error/root mean square error of B1I and B3I are 1.18 m/1.48 m and 0.84 m/1.10 m using DDM.The mean absolute error/root mean square error are 0.12 m/0.15 m and 0.10 m/0.12 m respectively using carrier phase delay.Due to the difference in signal characteristics,the accuracy of DDM altimetry B3I is 28%higher than that of B1I,and the accuracy of carrier phase delay altimetry B3I is slightly better than that of B1I,with no obvious difference between the two.Both B1I and B3I reflected signals are demonstrated to be suitable for retrieving sea surface height in this experiment,which compares the differences in retrieval accuracy between B1I and B3I related to signal characteristics and altimetry method.